Rotary gear pump



Dec. 29 u 1925.

J' L' DEVON ROTARY GEAR` PUMP Filed Far. 14, 1925 ATTQRNEY ROTARY GEAR PUMP Filed Feb. 14, 1925 2 Sheets-Sheet 2l Patented Dec. 29, 19125.

UNITED STAIES JOSEPH L. DEVON, or ATLANTA, GEORGIA.

ROTARY GEAR PUMP.

Application led February 14, 1925. Serial No. 9,269.

To all whom it may concern:

Be it known that I, JOSEPH L. DEVON, a

citizen of the United States, residing at Atlanta, in the county of Fulton and State of Georgia, have invented new and useful Improvements in Rotary Gear Pumps, of which the following is a specification.

The object of my said invention is to improve the waterdrawing ability of rotary gear pumps by the provision in combination with the idler or driven gear of such a pumpr of any appropriate braking attachment calculated to retard and-prevent too free turning of said idler or driven gear, and in that way preclude said gear breaking contact with the drivin gear with which it is meshed, such brea ing of contact being objectionable because it allows air to slip back from the discharge chamber of the pump to the suction chamber thereof, thereby preventing the pump from developing suiicient vacuum to draw water from overboard suction.

The accompanying drawings show one form or embodiment of my invention capable of carrying out the'underlying principles thereof. v

In said-drawings:- v

Figure lis a top plan view of a rotary gear pump, mounted on the frame or chassis of adire-engine automobile orother vehicle; l v

Figure 2 is a view in endelvation, a portion Aof the pump being broken away and `one Yof the members of the chassis being shown insection.

Figure 3 isa fragmentary detail view, partly in section and partly in elevation, of part ofthe brakingmechanism.

Figure 4 is a fragmentary view in elevation of the pump with the side removed to show the gears.

Figure 5 is a fragmentary view, in section, on the line 5-5 of Figure 2, the brakeband and operating mechanism therefor being removed; Vand Figure 6 is a detail view of the brakeband rocker. 1

In the drawings, it will be understood that the pump is not shown in detail, only such parts thereof being shown as are necessary to an understanding of my invention.

Referring now in detail, to the drawings 1 designates the driving-gear of a rotary .lyy constructed, there gear pump, such as is used on lire-engines, so called', of municipal fire departments, and 2 the driven gear thereof, mounted, respectively` on shafts 3 and 4. It will be noted, by reference to Figure 4, that, as customari- 1s amount of clearance between the meshing teeth, as shown at A. When drafting water, it is necessary of course, to eXpel air from the suctionfpipe and suction chamber, and, sometimes, on a lift of ten feet or more, the pump fails; because, in or'- derl to discharge air from the suction faster than -it will slip back into it from the discharge, the pump must be lrun at such speed that the gear-teeth break contact at the point V, making an opening for air to slip back into the suction from the discharge chamber.

When this form of pump is brand new, the packing 5 is tight enough on the shaft 2 to have the edect of a brake, and so, by preventing this vibration, holds the teeth constantly in contact. However, when this packing becomes a little worn and smooth from wear, it does not grip the shaft so a considerable tightly and then driven gear 2 breaks contact with driving gear l at the point V, and the discharge chamber. A braking attachment prevents this, as will be apparent from a reading of the construction and operation thereof, and at this point I desire it distinctly understood that it is within the f purview of my inventionvto employ any type of braking means compatible with the purpose of my invention, the salient feature of which consists in combination with the driving and driven meshed gears of a rotary gear pump, of braking means appropriately applied to the driven or idler gear with a view to retarding therotation of said gear and thereby averting or preventing lbreaking of contact between the said gear and the driving gear, for the purpose indicated.

To adapt the pump for use in connection with the herein disclosed s ecic and specifically advantageous bra ing attachment, which constitutes the subject of my Letters Patent No. 1,461,084, dated July k10, 1923, the driven ear shaft 2 is extended back through the earing retainer and dust-cap 6, and is provided wlth an exteriorly projecting reduced end 2*. On said end is mounted a drum 7, around which asses a brakeband 8, the free ends 8 of whic are looped around pins 9, passing through four ears 10 arrangedin two pairs, onepair toward each end of a sleeve 11 rotatably mounted on a fulcrum pin 12 secured at one end thereof in bearings 13 detachably secured to one of the cross braces B of the side frame members or channel bars C, of the chassis of the fire-engine. The sleeve 11 and the two pairs of ears 10 form part of a rocker or lever 14 having a web 15, the pin 12 constituting the fulcrum of the lever. The lever resembles somewhat, a bell crank lever of the coiiventional form, but is a modiied and peculiar form thereof. .Instead of one short arm, as in the conventional bell crank lever, my lever has two pairs of short arms (the ears 10) and theears ofV each pair are `connected :by pins 9. The rlower end of vthe lever is pivotally secured, as at 16 to asocket member 17,'having a screw threaded socket, in which maybe screwed a pull-rod118, having a screw-threaded end 19. :The rod projects Vaxially into a tubular member 20, having a pair L of lateral arms 21 projecting through registering slots 22, 23 in kone of the channelibarsC and a -wear plate 24, respectively. The wear plate is disposed eX- teriorly. ofthe channel bar` C as shown in Figure 2,) and suitably secured thereto.

-A cam lever 25 is fulcrumed on a pin 26 projecting` vthrough the lever and through the arms 21, and has the curved camface 27 bearing against the wear plate'24.

The-tubular member20 may-work in the cylindrical bore of a guide member 28.

The guide member 28 and the wear plate 24 aresecured to the channel bar C, preferably by common mean-s, such as screws 29.

-One of the open ends of the tubular member 20 is eXteriorly threaded and alscrew closure cap 30 is screwed on'such threaded end and is provided with a central aperture through which the pull-rod18 projects.

The end of Vthe pull-'rod 18 within the tubular member/207m provided witha disk head 31. against which oneend of a coiled spring-32 bears,the-other end of said spring bearing against the capBO. Thespring encircles'the rod 18 as shown.

It 4will be noted that the attachment or braking device described is very simple and compactand-that in operation ,-by pulling down the lever 25, the 'brake 'band 8 is `of the lever 25, it does not pull directly on the rod 18, but on the spring 32, thereby insuring uniform pressure on the brake drum. The lever 25 may be conveniently Voperated by a fireman standing on the ground beside the fire-engine` the fireman pulling the lever to apply the brake until thepump .is primed andthe water is being discharged. The brake has then served its purpose and should be thereupon released to prevent wear on the brake band and drum. Y Having thus fully described my invention, the many advantages thereof will be apparent, especially to those skilled in the art to which it pertains. It is obvious that many mechanical changes especially in detail, may be made in the particular form of device disclosed but such changes do not necessarily depart from the spirit of the invention or sacrifice any of its advantages and all such as come within the terms of the appended claims fall within the purview of the invention.

Having Idescribed my invention, what I claim and desire to secure by Letters-Patent,

1. A rotary gear pump having driving and driven meshedgears, and brake means for cooperation with the driven gear for the retardation Vof said gear with aview to vdriven meshed gears, a frame, `rotating shaft fixed to the driven gear,.and an operative controlled brake for said shaft.

1. The combination with the driving and driven meshed gears of a rotary gear pump, of a braking attachment for cooperation with Y the 'driven gear.

In testimony whereof I affix my signature.

lvJOSEPH L. DEVON.

It will. 

